It's not scary at all. You just stand there and resurrect vampires into liches + mummies + a hero until their maximum HP is less than 20, or even better, down to 1, and then any attack on any unit will fully heal the vampires. (And you can also just kill the angels first, haha).
I don't agree with the Elrath embodiment. In the last mission, I just one-shotted him with vampires. I had so many of them there. But I'm just a hardcore player; every battle is a new week of dark energy.
Also, I agree about the voice acting. I think I heard that there are 3 people helping with the voice acting, but even if the author wants to update the voice acting, it will still take another month, or even more.